Draft gear rigging



Dec. 2o, 1960 a G GUNS 2,965,246

DRAFT GEAR RIGGING Filed April 4, 1958 4 Sheets-Sheet V1 Ja ,15 JI.

INVENTOR. 55,?65/ 6T 6am/5 Tram/5K9.

Dec. 20, 1960 s. G. GUlNs DRAFT GEAR RIGGING 4 Sheets-Sheet 2 Filed April 4, 1958 NN WN .W\ WN IQN *N NN MIN MMM; f MM5;

JEEGE/ 6' 2f/Ns BY Dec. 20, 1960 s. G. GulNs DRAFT GEARRIGGING 4 Sheets-Sheet 3 Filed April 4, 1958 INVENTOR 55265/ G Gz//N BYM .flllllllllillllIllllllla illlllllfllllllllll Dec. 20, 1960 s. G. GUINS DRAFT GEAR RIGGING 4 Sheets-Sheet 4 Filed April 4, 1958 INVENTOR.

55H66/ 6am/J BY @wf mw ATTORNEYS `2,965,246 l DRAFT GEAR RlGGING Sergei G. Goins, Olmsted Falls,V Ghia, assignor to The Chesapeake and Ohio Railway Company, Cleveland,

This invention krelates todraft gear rigging for railway cars and more particularly to arrangements for increasing the energy-absorbing capacity Iof such rigging `for forces imposed upon it by bufhng blows on the coupler.

The problem of increasing4k or decreasing'thervelocity of the'cars is involved in the operation of moving goods andpeople about by railway cars. The rate of change of velocity is a function. of the impact force required to accomplish it, and in railroading, the changeof Velocity of a railway car is accomplished by pulling or pushing. Those impacts imposed by pulling are known in railroad parlance as draft forces, andv those impacts imposed by pushing a railway carareknwn as bufng forces.

It is common practice to4 absorb the impact of both draft forces and buing forces by means of draft gear rigging built-into the cars. Briefly, draftgear rigging for arconventional railway car embodies Va coupler or couphng member at each end ofthe car and an associated cushioning unit disposed between center sills' comprising a longitudinal center member of the underframe. The

bufhng or draft forces imposed upon a coupler are trans-i mitted tov the cushioning unit associated witliit which reduces the rate of 'changeof velocity or the impact and then transmits the applied force through appropriatevstop members to the center sills of the railway car. f n irn-v pact appliedto a coupler at one Yend of ua car is absorbed only by` its associated cushioning unit andthen transmitted to the centermernber at some point near thatend of theV car. fore, buing forces stress the center member entirely in compression while the draft forces stress the center'member entirely intension.

Of the two forces thus imposed upon the draftl gear rigging, the blow type or b ufng force isgenerallythe greater. Maximum buiiing forces. are generallylenc'oun-- tered during` switching operations when a vrailway car is placed in motion by shunting or humping.' During these operations, the shunted or bumped caris allowed to coast under thevelocity imparted to it by the engineer' gravity untiljit reaches a stop or a standingl canon'tlietrz'ik'zky to which it has been directed, at which timethe moving cars velocity is sharply decreased and a high bufhng impact force is produced.Y u

It can be seen that the speed at which a railway car caribe shunted or humped with due regardfor its contents is limited by the energy-absorbing capacity offits draft gear rigging. The limitation on the shunting and-humping speedsv is an important factor in determining the amount of time and money that is required to make up a train or rearrange the cars of a train. If thecars could be shuntedy or bumpedy at a higher speed, an appreciable amount4 of time and money would be saved.` While an increase in the energy-absorbing capacity of each of the independentlyY 'actingiicu's'hioning'f units ofy a conventional draft rigging would accomplish this, a more economical way is to utilize the idle capacity available in a conventional railway car, i.e., the idle'capaci'ty of that cush- In conventional draft gear rigging,` 'there-U 2,965,24 Patented Dec. 20, 1960 2 ioning unit remote from the coupler receivingvthe impact on bufling.

The` principal object of my invention is, therefore, to provide a energy-absorbing capacity available in a conventional railway car forcushioning buiiing forces. Another object of my invention is to provide a draft gear rigging having sufficient capacity for absorbing the impact of draft forces. A further object of my invention is to provide draft gear rigging with increased energy-absorbing capacity for bufng 'impact forces that can be readily adapted to existing railway cars. invention is to provide draft gear rigging which utilizes the energy-absorbing capacity of the cushioning units at both ends of a conventional railway car for absorbing a bufng impact applied to one end of the car.

Other objects and advantages of my invention will become apparent from thefollowing description taken' together with the accompanying drawings of a preferred embodiment, in which:

Figure l is a plan view of a railway flatcar in which the arrangement of the primary elements of the structure of my invention are indicated in broken lines.

Figure 2 is a side elevation Yof the railway car shown in Figure l. i

Figure 3 is a fragmentary plan view, in enlarged scale, showing one of two identical ends of the draft rigging of my invention and'associated cushioning units disposed between thevcenter sills of a railway car.

Figure 4 is a fragmentary elevation view, in enlarged scale, showing the mechanism shown in Figure 3 with portions of the *runderframe'illustrated in vertical section.

Figure` 5 is a plan View showing, in simplified form,

the complete mechanism of the draft rigging of in. ven'tion disposed between the longitudinal sills of a'v railway car, shown inl horizontal section, in which themechanism is in a neutral position, i.e. when the car is at rest without being subjected to draft or'bufng forces.

Figurei is a planl view, like Figure 5, but showing the mechanism as it appears when the lrailway car is subjected to a lightbufng force.,

Figure 7 is 'a ,plan view like Figure 5 but showing the mechanismrwhen the railway car is subjected toa heavy bufling force.

Figurel 8 is a plank view like Figure 5 showing the mechanism as it appears when subjected to draft forces.4 Figure 9 is a fragmentary plan view similar to Figure.

only one unit to absorb the draft: force applied to oneY end of the car. This is done by providing a longitudinal compression member which transmits a portion of the buing forcesvappliedto the cushioning unit at one end of the car to the cushioningiunit at ythe other end of the car.

Referring now to the drawings, a generallayoutof the draft gear rigging rof my invention, as arranged in a railway flatcar C, is shown in Figures 1 and 2. In gen; eral, the draft gear rigging is disposed between a pair of parallel center sills-10 comprising the longitudinal center member of the cars underframe, and includes conventional cushioningunits ll'carried by yokes 12 located near each endof, the longitudinal center sills 10, a con-v ventional coupler 14- associatedy with each of the cushdraft gear rigging that utilizes allv of theV Still another object of my ioning units 11, draft lugs 15 and buing lugs 16 located outwardly and inwardly, respectively, of the cushioning unit for transmitting forces imparted to the cushioning unit to the longitudinal center sills 10. Extending 1ongitudinallybetween the cushioning units 11 isa longitudinal compression member 17 for transmitting bufling impact forces from one cushioning unit` to the other.

The details of the mechanism can best be seen in Figures 3 and 4 showing in plan view and side elevation, respectively, one of two identical ends of a preferred form of my draft gear rigging.

In Figure 3, the two parallel spaced apart center sills comprising the main longitudinal member of the underframe are shown in section. Lying between and connecting the ends of center sills 10 is a striker casting and coupler carrier 18 suitably apertured as at 19 to receive stem 20 of the coupler 14. The striker casting and coupler carrier 18 may be fastened to center sills 10 by any suitable means such as rivets 21. A yoke 12, disposed between the center sills 10 and between the vertically spaced carrier plates 22, is connected to stem 20 of coupler 14 by a horizontal draft key 23 in a conventional manner. The draft key 23 is inserted in suitably aligned slots in stem 20 and yoke 12 through slotted openings 24 in the center sills 10. The draft key receiving slot in yoke 12 is elongated in the usual manner providing some longitudinal lost motion in the connection between coupler stem 20 and yoke 12. The cushioning unit 11 is carried by yoke 12 in a conventional manner. The cushioning unit includes an outward follower plate 25 and an inward follower plate 26. Follower plate 25 is engaged by the butt of stem 20 of coupler 14 while follower plate 26 engages the inner side 27 of the inward end of yoke 16.

I The draft lugs of striker casting and coupler carrier 18 and the buflng lugs 16 limit the longitudinal movement of cushioning unit 11 with respect to the center sills 10. The bufling lugs 16 are attached to center sills 10 by any suitable means such as rivets 21. It will be noted that the draft lugs 15 and buliing lugs 16 are spaced apart a sufficient distance to provide for a certain amount of longitudinal movement of cushioning unit 11, this is of importance to my invention as pointed out below in the description of its operation. The compression member 17 is disposed between the yokes 12 and is carried in suitable guides 28 welded or otherwise suitably attached to center sills 10. Compression member 17 is preferably of tubular form, though members of other suitable transverse cross section may be employed. Preferably, a bufling block 29 is disposed in either end of compression member 17 for engagement with the inward end of yoke 12 and for the transmission of forces between the yoke and the compression member. I prefer that the compression member guides 28 be of sucient strength and number to prevent any columnar deflection of compression member 17 when subjected to compression stresses during normal operation. In length, the compression member 17, together with the associated buff-ing blocks 29, should be such that the bufng blocks 29 lightly engage the inward ends of each of the yokes 12 when no forces are applied to the couplers, disposing the cushioning units 11 in their relaxed or uncompressed condition toward draft lugs 15.

The operation of the draft gear rigging of my invention is illustrated in Figures 5 through 8 showing the mechanism in various conditions of operation.

Figure 5 depicts the draft gear rigging in the neutral condition of operation such as is experienced when no forces are being exerted on the couplers of the car. It will bevnoted that the cushioning units 11 are relaxed or uncompressed and that the follower plates 25 and 26 are spaced apart the full distance allowed by the yoke 12 carrying them. Bufng blocks 29 lightly engage the inward ends of each of yokes 12 disposing them outwardly Yso that the outward follower plate 25 of each of the cushioning units 16 approaches the draft lugs 15 at either end of the car. The butts of stems 20 of couplers 14 apply no force to the outward follower plates 25.

Figure 6 shows that condition of operation where a light bu'ing force is imposed upon the coupler 14 at the left end of the rigging as seen in Figure 6. The light buing force exerted in the direction indicated by the arrow on the stem 20 of the left-hand coupler 14 is applied through the stem or draw bar 20 to the outward follower plate 25 of the left-hand cushioning unit 11. As this force is applied, the cushioning unit 11 seeks to move inwardly or to the right while being compressed against the inward end of yoke 12 which, at the same time, transmits the originally applied buiiing force to lefthand bufiing block 29 through compression members 17 and from the right-hand buiiing block 29 to yoke 12 at the right-hand end of the car. The inward end of the right-hand yoke 12 engages follower plate 26 of its associated cushioning unit 11 moving it outwardly and compressing it upon engagement of follower plate 25 with draft lugs 15 at that end of the car. It will be seen that in the case of a light bufiing force, a portion of the energy-absorbing capacity of each of the cushioning units 11 is utilized to absorb the impact of the force and finally it is transmitted to the center sills 10 through right-hand draft lugs 15 stressing the center sills only in tension.

Figure 7 depicts that condition of operation encountered when a heavy buiiing force is applied to the left-hand coupler 14. As in the case of a light buiiing force, the impact is applied through the draw bar or stem 20 of the left-hand coupler to the left-hand cushioning unit 11 through its forward follower plate 25 and thence through its inward follower plate 26 to yoke 12 and to the left-hand buftlng member 29. Compression member 17 then transmits the force to the right-hand end of the car where it is applied to the right-hand cushioning unit 11 through buing member 29, the inward end of yoke 12 and inward follower plate 26. The right-hand cushioning unit 11 is moved to the outward end of its draft pocket so that follower plate 25 engages draft lugs 15 imposing a tension upon center sills 10. In the condition illustrated in Figure 7, the magnitude of the impact force applied to the left-hand coupler is suicient to compress the right-hand cushioning unit 11 suiciently so that the left-hand cushioning unit 11 and its associated yoke 12 are displaced inwardly until the left-hand inward follower plate 26 engages bufiing lugs 16 at that end of the car. Upon the engagement of the bufng lugs 16 by follower plate 26, a portion of the total force is transmitted to the center sills of the railway car and stresses them in compression. In the case of a heavy buiing force, the compression stress transmitted to the center sills is gen erally greater than the stress in tension transmitted thereto; but the net stress in the center sills in compression is of a magnitude that is appreciably less than the compression stressing of the center sills in a conventional draft gear rigging.

Figure 8 illustrates that condition of operation when a draft force or pulling force is applied to the ends of the car. As indicated by the direction of the arrow on the stem 20 of the couplers 14,-the yokes 12 connected to these stems by horizontal draft keys 23 are disposed outwardly of each end of the car. Thus, outward follower plate 25 engages its respective draft lugs 15. At such time, each of the cushioning units 11 is compressed between draft lugs 15 engaged by outward follower plate Z5 and the inward end of its associated draft yoke 12 engaged by inward follower plates 26. Compression member 17 lies idle in its guides between the two yokes. 1t can be seen that when a draft rforce is applied to one end only of 'the draft gear rigging of my invention, the energy-absorbing capacity of only one of the two cushioningunits in the rigging is utilized. Figures 9and l0 illustrate, in an enlarged scale,fthe details of a'modied form of'my invention. The general arrangement of the elements in these gures is like that member 30 with rear .follower plate ,26 of the adjacent vcushioning unit 11 and thereby allowing ,the transmission of buing forces directly fromthe rear .follower plate 26 to the bufng member .-30 and thence to the-compression member 17.

In this form of my invention, when a heavy bufiing blow is received ona coupler 14, compressing to capacity the cushioning l.unit 11 at the opposite end ofthe car, the Abuiiing stops '.16 o n lthe :near end .of the oar areengaged by shoulders 31 `on bufling .member .30, rather than ldirectly engaged by the inward follower plate `26 as in the preferred embodiment of my invention.

The modified .form `of `my .invention `illustrated in Figures 9 and 10 loperates in a manner similar to that of the preferred embodiment of -my invention as shown and described in connection with Figures through 8. The principal difference in .the two forms is .the means used to transmit forces between each cushioning unit and the longitudinal ,compression member. In the preferred-form,rthe .inward ,end of .the yokes is interposed between the cushioning unitsand the compression member; while in the modified form, the force is transmitted directly between the .cushioning units and the compression member.

It will be appa-rent from the foregoingdescription of lthe operation of thedraft .gear rigging of my invention under varying conditions, that the energy-absorbing capacity for buing forces 4is tgreatlyincreased by the utilization .of the capacity .of that cushioning unit at the end -upon which Ythe .force is imposed together with the ordi- Ynarily idle capacity of .the cushioning luniton the opposite `end of the car. Measuring .the energy-absorbing capacity of the cushioning units in terms of the difference `in their length :when in a relaxedoruncompressed condition and when .in .a fully-compressed condition. it can be seen -that A.if a singlecushioning .unit as utilized in a conventional draft gear .rigging shortens vin length 21/2 inches, the energy-.absorbing capacity ,of the draft gear rigging of my invention as measured by this shortening would be 5 inches. It will be noted that the inward .bufiing stops 16 must be so located with respect to each of their associated cushioning lunits 11when in the idle position .that upon the Ainitial impact of a bufling force, the inward follower plate 26 of the cushioning unit 11 first to receive the impact does not engage the inward buffing lugs 16 until the cushioni-ng .unit 11 at the opposite end of the vcar has been shortened or absorbed -a portion of the impact.

It is further apparent from the foregoing description .ofthe operation of t-he draft gear rigging of my invention that the net compression stress imposed upon the rcenter sills of the conventional railwaycar is less than the compressive stress imposed upon themin a conven- .tional draft gear rigging by the amount of the compressive stress transmitted through the compression member 17 to the opposite end of the car where it is imposed upon the center sills stressing them in tension. There are, of course, compression forces set up in the compression member 17, but this member is no part of the load bearing structure of the railway car and has as its sole pur- -pose the transmission of such compression forces. Furthermore, this member, in its preferred form, is a tubular column suitably carried and guided by guides 28 held by center sills 10 which prevent any substantial defiection of the column. This reduction in the net stress applied to the center sills 10 becomes a distinct advantage when my invention is built into a new car because the size of the center sills may be reduced.

'It will be seen that my invention is thus Areadily adaptable for use in existing cars having two conventional cushioning `units ,and therefore .the ,advantages vobtainett :by it are not 'limited ,to newly .built cars.

YIn connection with the building ofnew cars incorporat- `ing myinventiomhowever, an additional advantage .is obtained. 'Because that ,portion-of .heavy bufiing forces absorbed .by the near cushioning unit and applied to the .underframe of the carstresses the center member in compression and that portion transmitted tothe far cushionving unit and applied to the underfrarne of the car stresses the center member in tension, .the next .maximum stress in the center member of the railway carhas Ybeen found by experiment to be a compression stress of appreciably less magnitude than the maximum compression stress in the center member of a car having conventional draft rigging. Thus, in building anew car, the weight ofthe center member can be safely vreduced below that ordinarily required, this offfsetting at least in substantial part, the cost and weightadded to the car by the incorporation of other components of mymechanism.

Those skilled in the art will .appreciate that various other changes and -modifications can bemade in the preferred forms -of apparatus described herein without departing from Athespirit and scope of the invention.

I claim:

l. A draft gear rigging for a railway car having couplers, a conventional underframe embodying a pair of fixed center sills .and cushioning units disposed near the ends of the car, said fixed center sills V.being laterally spaced apart to accommodate saidcushioning units and being connected .at each end by members adapted to receive and support .the .stem .of .a coupler, each Aof said cushioning units Vbeing supported by said fixed center lsills and mounted for movement in vthe .space between said fixed center sills .and being operatively .connected with the stern of a coupler .extending into the space between said fixed center sills inwardly of saidconnecting member, said draft gear rigging .comprising a longitudinal compression member movable relative .to said .center sills and operatively interposed inwardly of and having `butting engagement .with said cushioning units and operable only in compression for .transmitting bufiing forces between said cushioning units, firststop .members Ymounted-on said fixed center sills outwardly .of .and .respectively associated with each of said cushioning units, said first stop members being engageable by .said associated Ycushioning unit for transmitting Ato said fixed .center sills draft forces applied to said associated cushioning unit yby said operatively connected coupler independently of said compression ,memberto stresssaid fixedcenter sills in tension, and for transmitting to saidlfixed center sills bufling forces applied to said associated cushioning unit `by said compression member .independently .of said operatively -connected coupler to stress said vfixed center sills .in tension, and second stop members fixed to said 'fixed center sills inwardly of and respectively Aassociated with each of said cushioning units, said second stop .members being engageable by said associated Lcushioning unit for .transmitting to said fixed center sills buing forces kapplied to said associated cushioning unit by said operatively connected 4coupler .to stress said fixed center sills in compression.

2. A draft gear rigging for la railway car having couplers, an underframe embodying a pair of fixed center sills and cushioning units disposed near the ends of the car, said fixed center sills being laterally vspaced apart to accommodate said cushioning units and being connected at .each end by a coupler carrier and striker casting apertured to receive and support the stem of a coupler, each of said cushioning units being supported by and between said fixed center sills and mounted for relative movement with said fixed center sills and being operatively connected with the vstem .of a coupler extending into the space between `said fixed center sills, said draft gear rigging comprising a longitudinal tubular compression member :disposed in the space between and movable relative to said fixed center sills and operatively interposed inwardly of and having butting engagement with said cushioning units and operable only in compression for transmitting bufng forces between said cushioning units, guide means mounted on said xed center sills cooperating with said compression member to limit lateral deflection of said compression member under compressive load, first stop members mounted on said fixed center sills outwardly of and respectively associated with each of said cushioning units and engageable by said associated cushioning unit, and second stop members mounted on said fixed center sills inwardly of and respectively associated with each of said cushioning units.

3. A draft gear rigging for a railway car having couplers, a conventional underframe embodying a pair of fixed center sills and cushioning units disposed near the ends of the car, said fixed center sills being laterally spaced apart to accommodate said cushioning units and being connected at each end by coupler carrier and striker castings apertured to receive and support the stem of a coupler, each of said cushioning units being supported by and between said fixed center sills and mounted for relative movement with said fixed center sills and being operatively connected with the stem of a coupler extending into the space between said fixed center sills through said apertured coupler carrier and striker castings, said draft gear rigging comprising a longitudinal tubular compression member disposed in the space between and movable relative to said fixed center sills and operatively interposed inwardly of and having butting engagement with said cushioning units and operable only in compression for transmitting bufring forces between said cushioning units, guide means mounted on said fixed center sills cooperating with said compression member to limit lateral deflection of said compression member under compressive load, first stop members mounted on said fixed center sills outwardly of and respectively associated with each of said cushioning units, said first stop members being engageable by said associated cushioning unit for transmitting to said fixed center sills draft forces applied to said associated cushioning unit by said operatively connected coupler independently of said tubular compression member to stress said fixed center sills in tension, and for transmitting to said fixed center sills bufling forces applied to said associated cushioning unit by said compression member independently of said operatively connected coupler to stress said fixed center sills in tension, and second stop members mounted on said fixed center sills inwardly of and respectively associated with each of said cushioning units, said second stop members being engageable by said associated cushioning unit for transmitting to said fixed center sills buing forces applied to said associated cushioning unit by said operatively connected coupler independently of said compression member to stress said xed center sills in compression.

4. A draft gear rigging for a railway car having couplers, keys, a conventional underframe embodying a pair of fixed Center sills having a single laterally aligned key slot adjacent each end, yokes disposed near the ends of the car and a cushioning unit having inward and outward follower plates associated with and carried by each yoke, said fixed center sills being longitudinally parallel and laterally spaced'and connected at each end by a lateral connecting member adapted to receive and support the stem of a coupler, each of said yokes being supported by and between and for relative movement with the fixed center sills, a coupler operatively connected to eachyoke by a key extending through the coupler stern, the yoke and two aligned key slots in said fixed center sills and engageable endwise withthe outward follower plate of the associated cushioningiunit Yto apply inwardly and outwardly directed forces on the associated cushioning unit, aV longitudinal compression member vsupported by and between and movable relative to the fixed center sills oper atively interposed and having vbutting engagement with said cushioning units and operable only in compression for transmitting buiiing forces between the cushioning units, draft lugs mounted on and extending laterally into the space between the fixed center sills outwardly of and associated with each of the cushioning units, the draft lugs being engageable by the outward follower plate of the associated cushioning unit for transmitting to the center sills independently of a key outwardly directed `forces applied to the associated cushioning unit, and bufling lugs mounted on and extending laterally into the space between the fixed center sills inwardly of and associated with each of said cushioning units, the butiing lugs cooperating respectively with the draft lugs associated with said associated cushioning units and being longitudinally spaced apart from the cooperating draft lugs a distance greater than the length of one of said cushioning units when relaxed for transmitting independently of said compression member inwardly directed forces applied to said cushioning units to the xed center sills.

5. A draft gear rigging for a railway car having couplers, keys, a conventional underframe embodying a pair of fixed center sills having a single laterally aligned key slot adjacent each end, yokes disposed near the ends of the car and a cushioning unit having inward and outward follower plates associated with and carried by each yoke, said fixed center sills being longitudinally parallel and laterally spaced and connected at each end by a lateral connecting member adapted to receive and support the Stem of a coupler, each of said yokes supported by and between and for relative movement with the fixed center sills, a coupler operatively connected to each yoke by a key extending through the coupler stem, the yoke and two aligned key slots in said fixed center sills and engageable endwise with the outward follower plate of the associated cushioning unit to apply inwardly and outwardly directed forces on the associated cushioning unit, a longitudinal compression member supported by and between and movable relative to the fixed center sills operatively interposed said cushioning units and having butting engagement with the inward ends of their yokes for transmitting buiing forces between the cushioning units, draft lugs Amounted on and extending laterally into the space between the fixed center sills outwardly of and associated with each of the cushioning units, the draft lugs being engageable by the outward follower plate of the associated cushioning unit for transmitting to the center sills independently of a key outwardly directed forces applied to the associated cushioning unit to the center sills, and bufiing lugs mounted on and extending laterally into the space between thefixed center sills inwardly of and as sociated with each of said cushioning units, the buing lugs cooperating respectively with the draft lugs associated with said associated cushioning units and being longitudinally spaced apart from the cooperating draft lugs a distance greater than the length of one of said cushioning units when relaxed for transmitting independently of said compression member inwardly directed forces applied to said cushioning units to the fixed center sills.

6. A draft gear rigging for a railway car having couplers, keys, a conventional underframe embodying a pair of fixed center sills having a single laterally aligned key slot adjacent each end, yokes disposed near the ends of the car and a cushioning unit having inward and outward follower plates associated with and carried by each yoke, said fixed center sills being longitudinally parallel and laterally spaced and connected at each end by a lateral connecting member adapted to receive and support the stern of a coupler, each of said yokes supported by Vand between and for relative movement with the fixed center sills, a coupler operatively connected to each yoke by a key extending through the coupler stern, the yoke and two aligned key slots in saidxed center sills and engageable endwise with the outward follower plate of the associated cushioning unit to apply inwardly and outwardly-directedforces on the associated cushioning unit, a longitudinal compression g member supported by and between and movable relative to the fixed center sills operatively interposed said cushioning units and having butting engagement with their inward follower plates and operable only in compression for transmitting buing forces between the cushioning units, draft lugs mounted on and extending laterally into the space between the xed center sills outwardly of and associated with each of the cushioning units, the draft lugs being engageable by the outward follower plate of the associated cushioning unit for transmitting to the center sills independently of a key outwardly directed forces applied to the associated cushioning unit to the center sills, and buing lugs mounted on and extending laterally into the space between the fixed center sills inwardly of and associated with each of said cushioning units, the bufling lugs cooperating respectively with the draft lugs associated with said associated cushioning units and being longitudinally spaced apart from the cooperating draft lugs a distance greater than the length of one of said cushioning units when relaxed for transmitting inwardly directed forces applied to said cushioning units to the fixed center sills.

References Cited in the le of this patent UNITED STATES PATENTS 

